RIVERSIDE, Calif. -

The average price of a gallon of self-serve regular gasoline in the Inland Empire rose Friday for the 13th time in 15 days,  increasing 2 cents to $3.962.

   The average price in Riverside and San Bernardino counties has risen  14.7 cents over the past 15 days, including 2.8 cents on Thursday, according to figures from the AAA and Oil Price Information Service.

   The average price is 11.8 cents more than one week ago and 4.3 cents higher than one month ago. However, it is 17.5 cents less than it was one year ago, mainly thanks to a stretch of 29 decreases in 30 days that ended Aug. 30.

   The rising pump prices follow a spike in wholesale gasoline prices caused by California refinery outages, according to Jeffrey Spring of the  Automobile Club of Southern California.

   ``Other states are seeing gas price decreases, but because California's fuel supply is limited mainly to its own refineries, any production issues at  them immediately send pump prices soaring,'' Spring said.

   ``In the past week, three Northern California refineries and one in Southern California have reported outages affecting production.''